Amazing, thanks!
I didn't recognize it as Moen due to the handle adapter and sleeve kit.
For the next person who searches this thread, deep inside it was just a standard Moen #1248 cartridge.
(FYI, I never worked on this myself. It was a customer of mine that took it apart, then called me panicking. I would have instinctively taken the next nut off to look a little deeper. Its really annoying when they don't want to pay my rate, then, still expect free advice after they messed it up.)
Thanks again!